Four thousand customers were without power Sunday night. ComEd says the balloon made contact with a power line near Laramie and Belden.
When Mylar balloons touch a power line, their metallic properties cause a surge of electricity that leads to an outage.
ComEd suggests that people keep Mylar balloons tied down at all times. If you need to dispose of one, pop the balloon first to make sure all the helium is gone.
